How do i calulate aggression in Pokertracker?

[hemstock]

"MP1 is very laggy...62/25/4.80"

What does voluntarily put $ in pot VP$IP mean? Can you give me an example please because I cant undertand this and why is it so importand. Then what does the second stat stand for (the 25 in the above example). How can I calcualate these stats in pokertracker for each player on my table so that I'll have to take it in concideration when I have to make a decision against them?